This invention is directed to a light leakage barrier for a back lighted indicator of a control knob or button. The conventional back lighted indicator, or light pipe as it is commonly called, is flush with or projects beyond the surface of the core of the conventional injection molded control knob or button in which it is mounted either through an opening in the core wall or in a window housing such as a fin which is formed integrally with and projects beyond the core wall. The exposed sides of the back lighted indicator or the side walls of its fin, which are not intended to transmit light to a viewer, are obscured by an opaque outer plastic covering. This molded, opaque outer covering overlies or abuts the edges of the light pipe indicator or the walls of its fin to provide a sharp cutoff and thus a high clarity definition for the back lighted indicator. When a back lighted indicator is provided in a knob which has a separately formed or assembled cover and/or a decorative trim ring, it has been difficult to prevent light leakage through the gaps which occur where the back lighted indicator projects through an opening in the cover or an opening in the decorative trim ring and this light leakage presents an irregular or ragged indicator to the viewer.
Therefore, an object of my invention is a light leakage barrier for the gaps which occur between a decorative trim ring, a cover and a light pipe indicator in a composite knob or button.
Another object of my invention is a light leakage barrier for a back lighted indicator which barrier is formed simultaneously with a gripping overlay applied to the skirt of a knob or the outer wall of a button.
A further object of my invention is a light barrier which is adaptable to both back lighted indicators which are flush with or project through openings in the core and to such indicators which are located in window housings such as fins which project beyond the outer surfaces of the core.
Other objects of the invention will be found in the following specification, claims and drawings.